Question

a1 и d надо найти если а3=-5,а19=59

Answer 1

a3=-5, a19=59, a1=?, d=?
a19=a3+16d, 16d=a19-a3, 16d=59-(-5)=64, d=64/16, d=4
a3=a1+2d, a1=a3-2d, a1=-5-2.4=-5-8=-13,a1=-13
Otvet:a1=-13, d=4